This document discusses accommodation and presbyopia. It defines accommodation as the ability of the eye to change focus from distant to near objects by changing the shape of the lens. Accommodation decreases with age in a process called presbyopia as the lens becomes less flexible. Presbyopia symptoms include difficulty seeing close objects clearly and can be treated with reading glasses, bifocal glasses, or multifocal contact lenses to restore near vision. The document also covers topics like ciliary muscle function, amplitude of accommodation measurement, and factors affecting presbyopia.
this PPT summarizes the echanism, theories, components of Accommodation as well as the physiological decline of it giving rise to Presbyopia. It aims to deliver the clinical features, developmental theories and evidence based trend of correcting Presbyopia.
A lecture on the current techniques (mainly surgical) for the correction of Presbyopia. This includes information on static and dynamic surgical and non surgical approaches.
this PPT summarizes the echanism, theories, components of Accommodation as well as the physiological decline of it giving rise to Presbyopia. It aims to deliver the clinical features, developmental theories and evidence based trend of correcting Presbyopia.
A lecture on the current techniques (mainly surgical) for the correction of Presbyopia. This includes information on static and dynamic surgical and non surgical approaches.
This presentation is prepared in the process of me teaching Visual Optics for graduate level optometry students. It narrates the type, clinical manifestations, clinical assessment and treatment of Aniseikonia.
The human eye is one of the most valuable and sensitive sense organs in the human body. It enables us to see the wonderful world and colours around us.
Structure of eye:
The human eye has the following main parts:
Cornea: It is the transparent spherical membrane covering the front of the eye. Light enters the eye through this membrane.
Crystalline lens: The eyes lens is a convex lens made of a transparent, soft and flexible material like a jelly made of proteins.
Iris: It is a dark muscular diaphragm between the cornea and the lens. It controls the size of the pupil. It is the colour of the iris that we call as the colour of the eye.
Pupil: It is a small hole between the iris through which light enters the eye. In dim light, it opens up completely due to expansion of iris muscles, but in bright light it becomes very small due to contraction of iris muscles.
La chirurgie de la presbytie n'est pas toujours possible avec le laser. Il faut alors envisager une chirurgie du cristallin claire avec des implants multi-focaux. Ceux-ci permettent de corriger la vision de loin et près de manière définitive.
Management of visual problems of Aging by Ashith Tripathi Ashith Tripathi
This presentation contains headings - Visual performance in the ageing eye
Routine optometric and ocular examination of an older adult:
History
Ocular health examination
Visual acuity measurement
Refraction
Binocular vision
Visual field measurement
Colour vision
Management of vision problems in older adults
Frame requirement
Lens requirements
And special instructions etc.
This presentation is prepared in the process of me teaching Visual Optics for graduate level optometry students. It narrates the type, clinical manifestations, clinical assessment and treatment of Aniseikonia.
The human eye is one of the most valuable and sensitive sense organs in the human body. It enables us to see the wonderful world and colours around us.
Structure of eye:
The human eye has the following main parts:
Cornea: It is the transparent spherical membrane covering the front of the eye. Light enters the eye through this membrane.
Crystalline lens: The eyes lens is a convex lens made of a transparent, soft and flexible material like a jelly made of proteins.
Iris: It is a dark muscular diaphragm between the cornea and the lens. It controls the size of the pupil. It is the colour of the iris that we call as the colour of the eye.
Pupil: It is a small hole between the iris through which light enters the eye. In dim light, it opens up completely due to expansion of iris muscles, but in bright light it becomes very small due to contraction of iris muscles.
La chirurgie de la presbytie n'est pas toujours possible avec le laser. Il faut alors envisager une chirurgie du cristallin claire avec des implants multi-focaux. Ceux-ci permettent de corriger la vision de loin et près de manière définitive.
Management of visual problems of Aging by Ashith Tripathi Ashith Tripathi
This presentation contains headings - Visual performance in the ageing eye
Routine optometric and ocular examination of an older adult:
History
Ocular health examination
Visual acuity measurement
Refraction
Binocular vision
Visual field measurement
Colour vision
Management of vision problems in older adults
Frame requirement
Lens requirements
And special instructions etc.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
2. ACCOMMODATION
• Accommodation, the mechanism by which the eye changes focus from distant to
near images, is produced by a change in lens shape resulting from the action of the
ciliary muscle on the zonular fibers
• The lens substance is most malleable during childhood and the young adult years,
progressively losing its ability to change shape with age.
• After approximately 40 years, the rigidity of the lens nucleus clinically reduces
accommodation because the sclerotic nucleus cannot bulge anteriorly and change
its anterior curvature as it could before
3. According to the classic theory of von Helmholtz, most of the accommodative
change in lens shape occurs at the central anterior lens surface.
The central anterior capsule is thinner than the peripheral capsule, and the
anterior zonular fibers insert slightly closer to the visual axis than do the
posterior zonular fibers, resulting in a central anterior bulge with
accommodation.
The posterior lens surface curvature changes minimally with accommodation.
The central posterior capsule, which is the thinnest area of the capsule, tends to
bulge posteriorly to the same extent regardless of zonular tension
4. The ciliary muscle is a ring that, upon contraction, has the opposite
effect from that intuitively expected of a sphincter. When a sphincter
muscle contracts, it usually tightens its grip.
when the ciliary muscle contracts, the diameter of the muscle ring is
reduced, thereby relaxing the tension on the zonular fibers and
allowing the lens to become more spherical.
Thus, when the ciliary muscle contracts, the axial thickness of the lens
increases, its diameter decreases, and its dioptric power increases,
producing accommodation.
When the ciliary muscle relaxes, the zonular tension increases, the lens
flattens, and the dioptric power of the lens decreases.
The accommodative response may be stimulated by the known or
apparent size and distance of an object or by blur, chromatic
aberration, or a continual oscillation of ciliary tone.
5. Accommodation is mediated by the parasympathetic fibers of
cranial nerve III (oculomotor).
Parasympathomimetic drugs (eg, pilocarpine) induce
accommodation, whereas parasympatholytic medications (eg,
atropine) block accommodation.
Drugs that relax the ciliary muscle are called cycloplegics
6. The amplitude of accommodation is the amount of change in the
eye’s refractive power that is produced by accommodation. It
diminishes with age and may be affected by some medications
and diseases. Adolescents generally have 12–16 D of
accommodation, whereas adults at age 40 have 4–8 D. After age
50, accommodation decreases to less than 2 D. It is thought that
hardening of the lens with age is the principal cause of this loss
of accommodation, which is called presbyopia. Research is under
way into other possible contributing factors in presbyopia, such
as changes in lens dimensions, in the elasticity of the lens
capsule, and in the geometry of zonular attachments with age.
7.
8.
9. FAR POINT, NEAR POINT, RANGE AND AMPLITUDE OF ACCOMMODATION
• The nearest point at which small objects can be seen clearly is called near
point or punctum proximum and the distant (farthest) point is called far
point or punctum remotum. The distance between the near point and the
far point is called range of accommodation. The difference between the
dioptric power, needed to focus at near point(P) and to focus at far point
(R) is called amplitude of accommodation(A). Thus A= P-R
10. Stimulus for accommodation
• There is no single important stimulus for accommodation. All of the following
factors must be responsible in elicting the appropriate accommodative response.
1. Image blur
2. Apparent size and distance of object
3. Chromatic aberrations
4. Oscillation of accommodation
5. Scanning movements of the eye
11. REACTION TIME
• Reaction time refers to the time lapse between the presentation of an
accommodative stimulus and occurrence of the accommodative response.
• 1. Average reaction time for ‘far to near’ accommodation is 0.64
seconds.
• 2. Average reaction time for ‘near to far’ accommodation is 0.56
seconds.
• 3. Reaction time for accommodation is considerably larger than that for
the contraction of the pupil to light (0.26-0.30seconds). Reaction time of
convergence response is about 0.20 seconds
12.
13. ASSESSMENT OF ACCOMMODATION
• accommodation is a unique mechanism by which our eyes can even focus
the diverging rays coming from a near object on the retina in a bid to see
clearly. Assessment of accommodation is of great diagnostic value in cases
of incomitant strabismus of non-paralytic origin. Assessment of amplitude
of accommodation can be made either by measurement of NPA or by use
of minus lenses.
14. MEASUREMENT OF NPA
NPA is measured using a near point rule such as RAF rule or prince’s rule. To
determine the NPA, a sliding target with 6/9 letters, numbers or fine lines is
moved from or towards the eye until the closest point is found at which it still
can be seen clearly.
During the examination, the patient has to wear his or her full optical
refractive correction. The NPA is determined first for each eye separately and
then for both eyes together. The NPA is measured in centimeters marked on
one side of the instrument bar. The side of bar marked in dioptres will
indicate the amplitude of accommodation in dioptres. The third side of the
bar shows the age corresponding to the accommodation.
e.g. if the patient reports that the point appears blurred at 25 cm, the dioptric
markings will show +4.0 D and the age of 40 years.
16. Measurement of amplitude of accommodation using minus
lenses
• This test is also performed first for each eye separately and then for both
eyes together, and during examination the patient has to wear his or her full
refractive correction. The patient is asked to fixate 6/60 symbol at a
distance of 6m, and minus lenses of progressively increasing power are
added before the eye till one can see the target clearly. The power of this
minus lens is equivalent to the amplitude of accommodation in dioptres.
17. PRESBYOPIA
• Presbyopia is the normal loss of near focusing ability that occurs with age.
Most people begin to notice the effects of presbyopia sometime after age 40,
when they start having trouble seeing small print clearly — including text
messages on their phone.
• You can't escape presbyopia, even if you've never had a vision problem before.
Even people who are nearsighted will notice that their near vision blurs when
they wear their usual eyeglasses or contact lenses to correct distance vision.
18.
19. Presbyopia symptoms
• When you become presbyopic, you either have to hold your smartphone
and other objects and reading material (books, magazines, menus, labels,
etc.) farther from your eyes to see them more clearly.
• when you move things farther from your eyes they get smaller in size, so
this is only a temporary and partially successful solution to presbyopia.
• If you can still see close objects pretty well, presbyopia can cause
headaches, eye strain and visual fatigue that makes reading and other
near vision tasks less comfortable and more tiring
20. What causes presbyopia?
• Presbyopia is an age-related process. It is a gradual thickening and loss of
flexibility of the natural lens inside your eye.
• These age-related changes occur within the proteins in the lens, making the
lens harder and less elastic over time. Age-related changes also take place
in the muscle fibers surrounding the lens. With less elasticity, it gets
difficult for the eyes to focus on close objects.
21. • PRESBYOPIA TREATMENT
Eyeglasses
• Eyeglasses with progressive lenses are the most popular solution for presbyopia for most people over age 40. These line-free multifocal
lenses restore clear near vision and provide excellent vision at all distances.
• Another presbyopia treatment option is eyeglasses with bifocal lenses, but bifocals provide a more limited range of vision for many
people with presbyopia.
• It's also common for people with presbyopia to notice they are becoming more sensitive to light and glare due to aging changes in their
eyes. Photochromic lenses, which darken automatically in sunlight, are a good choice for this reason.
• Reading glasses are another choice. Unlike bifocals and progressive lenses, which most people wear all day, reading glasses are worn
only when needed to see close objects and small print more clearly.
• If you wear contact lenses, your eye doctor can prescribe reading glasses that you wear while your contact lenses are in. You may
purchase reading glasses at an eyewear retail store, or you can get higher-quality versions prescribed by your eye doctor.
22. Contact Lenses
• People with presbyopia also can opt for multifocal contact lenses,
available in gas permeable or soft lens materials.
• Another type of contact lens correction for presbyopia
is monovision, in which one eye wears a distance prescription, and
the other wears a prescription for near vision. The brain learns to
favor one eye or the other for different tasks.
23. • Magnification Formulae
• Linear Magnification
• The linear magnification produced by a spherical lens can be calculated from the basic formula:
• Linear magnification= I/O=V/U
• where I is the image size, O is the object size, v is the distance of the image from the principal plane,
• and u is the distance of the object from the principal plane (Fig. 5.9).
•
24.
25. • Magnification
• Traditionally, three types of magnification are discussed: relative distance
magnification, relative size magnification, and angular magnification.
• a. Relative Distance Magnification
• The easiest way to magnify an object is to bring the object closer to the eye.
By moving the object of regard closer to the eye, the size of the image on the
retina is enlarged.
• Children with visual impairments do this naturally. Adults will require reading
glasses to have the object in focus.
• Relative Distance Magnification = r/d where r = reference or original working
distance and d = new working distance
• Example
• Original working distance = 40cm
• New working distance = 10cm
• Relative Distance Magnification (RDM) = 40/10 = 4x
26. • Magnification occurs because the lens strength requires the individual
using them to hold things closer to have the object in focus.
• b. Relative Size Magnification
• Relative size magnification enlarges the object while maintaining the same
working distance, for instance, as observed with large print.
• Relative Size Magnification = S2/S1 where S1 = original size and S2 = the
new size
• Example
• Original size = 1M
• New size = 2M
• Relative Size Magnification (RSM) = 2/1 = 2x
27. • Depth of Focus
• Depth of focus describes the image location range where the image is
clear when focused by an optical system. Outside this range, the image
will be significantly blurry. However, within this few millimeters range, the
image appears quite sharp.
• Depth of Field
• Depth of field is the same principle for objects as the depth of focus is for
images. When an optical system such as the camera is focused on an
object, nearby objects are also, in focus, inside the camera’s depth of field.
Objects outside of the depth of field will be out of focus.